Bone marrow aspirations (BMA's) are highly painful and aversive procedures for pediatric cancer patients. Previous research by the investigators has indicated the efficacy of a Cognitive Behavior Therapy Package (CBTP) in reducing childrens distress during BMA's. However, the CBTP is not effective for all children nor does it eliminate distress for those children who do fine it helpful. The aim of the current proposal is to evaluate general anesthesia (nitrous oxide and halothane) as compared to the CBTP in terms of patient, parent, and staff distress; cost/benefit ratio and "consumer preference". Attitudes of health care providers towards pain in children and towards psychological intervention vs. general anesthesia for BMA's will be evaluated as well. Subjects will be approximately 50 pediatric cancer patients undergoing at least three consecutive BMA's. A pre-test or baseline observation of children's distress during BMA's will be conducted and then children will be randomly assigned to one of two sequence groups. All children will receive both interventions. Assessment measures for the children will include: a) behavioral distress prior to BMA, b) self-reported fear prior to and after BMA, c) pulse rate upon arrival in treatment room, d) parent questionnaire of childrens' behavioral after-effects 24 hours following procedure, e) child mental status after BMA, f) physical side effects (nausea, vomiting, etc.), and g) preference for CBTP vs. general anesthesia at end of study. Parent and staff anxiety will be measured using self-report anxiety measures behavioral observation, and pulse rates. Provider attitudes will be measured by a telephone survey. Data analysis will be conducted using a 2 (sequence group)x2 (intervention condition) repeated measures multivariate analyses of covariance with pretest scores serving as covariates. Analyses will also be conducted to predict which children benefit most from general anesthesia.